Litologia i własności surowcowe baranowskich glin kamionkowych

Abstract

Wykorzystując szereg metod analitycznych zbadano pięć próbek bruzdowych czerwonych glin baranowskich, które reprezentują trzy odmiany litologiczne skał ilastych eksploatowanych w kopalni Bararanów k. Suchedniowa. Kopaliną główną występującą w pokładach VI i V są żelaziste, mułkowe iłowce illitowo-kaolinitowe mające cechy plastycznych, czerwonych glin kamionkowych gatunku P. Stwierdzono, że glinom tym towarzyszą zlityfikowane iłowce mające taki sam skład mineralny i własności termiczne lecz nie spełniające pod względem składu granulometrycznego kryteriów stawianych glinom kamionkowym. Zidentyfikowano ponadto występowanie "spieku", tj. twardych granul ilasto-hematytowych tkwiących w masie ilastej. Wyniki badań właściwości ceramicznych wskazują na przemysłową przydatność zlityfikowanego iłowca, jak i "spieku" - traktowanych obecnie jako odpad produkcyjny.

LITHOLOGY AND RAW MATERIAL PROPERTIES OF THE BARANÓW STONEWARE LOAMS

The Baranów loams, cropping out at the Góra Baranowska Hill in the vicinities of Suchedniów (Fig. 1), were exploited for over a hundred years. Under that name are lumped various Lower Triassic rocks differing in mineral composition, colour, and possible uses. The Baranów deposit is built of layers of quartz, usually fine-grained sandstones with clay-siliceous cement, a few to about a dozen meters in thickness, separated by clay layers from one to 22 m in thickness. The latter were assigned to six layers (Fig. 2), numbered from I (the youngest) to VI (the oldest).

The rocks, Lower Rhot in age, dip to NNW at the angle of 6-10°. Because of such structure of the deposit, the layer I is exposed in its northern part, and the older appear successively towards the south. The monoclinal structure is disturbed by faults assignable to two systems: one, comprising faults NWW-SEE oriented and with downthrows up to about a dozen m, and the other, comprising faults NS oriented and with downthrows below 4 m. Fault planes are inclined at the angle of 80-90°. The analyses covered five samples form the layer (Fig. 3). The sampled rocks were found to be macroscopic ally different in lithology. The samples B-1 and B-4 are almost identical in granulometric composition (Table I, the sample B-2 is characterized by the lowest content of clay-size grains, and the sample B-3 (called as "agglomerate") - by content of grains over 0.06 mm in size as high as 20.8 %.

Coarse grains found in the sample B-2 represent hard fragments of red clay mudstone with well visible and hematite-coated slip planes, fragments of darker-coloured claystone, and single hematite and single hematite spherules. The sample B-3 yielded very hard dark brown gleamy granules as well as brown ones with mat surface.

Mineral composition of all the samples is found to be quantitatively identical. X-ray analyses (Fig. 4) showed presence of kaolinite, micaceous mineral of the illite type, chlorite, quartz, hematite, anatase, gypsum, sodium-calcium plagioclases of the albite-oligoclase series, and possibly zeolites of the heulandites series. Moreover, thermic analyses (Figs. 5 and 6) revealed presence of goethite. The normative quantitative mineral composition was calculated on the basis of the obtained chemical composition (Tables 2 and 3). Subsequently, ceramic properties of the samples B-1, B-2, and B-3 were tested by the fritting curve method (Figs. 7 - 9). Table 4 shows technological properties of the studied rocks, and Table 5 - physical properties of ceramic material obtained after fritting.

Because of similarities in mineral composition of the studied rocks, ranges and intervals of fritting for individual types of ceramic materials appear almost identical. In turn, differences in lithology of the rocks significantly influence content of water, shrinkage, the mode of deformation and breakage, and particularly physical properties of ceramic material. The mineral composition of material obtained by fritting at various temperatures, as established by the X-ray methods, appears rather stable and not much varying. Fig. 10 shows changes in content of major components. The analyses showed presence of quartz, crystot.allite, mullite, and hematite.

The sample B-6 represents the layer V, and the sample B-5 - a bed occurring between the layers IV and V. Table 5 shows granulometric composition of these samples. X-ray (Fig. 11) and thermic (Figs. 12 and 13) analyses revealed presence of the same minerals as in samples from the layer VI (except for goethite). Table 7 shows technological properties of the rocks, established with the use of the fritting curve method (Figs. 14 and 15), and Table 8 - physical properties of the obtained ceramic material.

The available data show that the Baranów loams consist of three varieties of clay rocks, differing in lithology. The first of these varieties is represented by red ferruginous silty kaolinite-illite claystones. The claystones easily absorb water and undergo natural disintegration, which facilitates obtaining a mass with very good moulding properties. The process of fritting of these rocks proceeds gradually along with rise of temperature, with the peak at 1150°C. Material fritted at temperature of 1100-1150°C is characterized by soakability close to zero and high strength to compression, equal 37-44 kN/cm².

The second variety is represented by claystone resembling the former in mineral composition but differing in more advanced lithification. The content of coarse components is so high that the use of this rock requires a preliminary grinding. The third variety is represented by accessorily occurring conglomerate built of clay-hematite granules, very poorly cemented with silty-clay mass. The conglomerate is known under local name of "spiek" (agglomerate). It may be used as one of components of mass when technology involves grinding of raw material.